Fix: some cases of bone scale were not handled correctly in new FBX importer

- Was not consistently adjusting for bone adjust_post_scale
- Map fbx node "igore parent scale" to Blender bone "inherit scale: none"

Pull Request: https://projects.blender.org/blender/blender/pulls/138204

source/blender/io/fbx/importer/fbx_import.cc

@@ -289,7 +289,6 @@ void importer_main(Main *bmain, Scene *scene, ViewLayer *view_layer, const FBXIm
    * cause armatures/skins to not import correctly, when inserted in the middle of bone chain. */
   opts.geometry_transform_handling = UFBX_GEOMETRY_TRANSFORM_HANDLING_MODIFY_GEOMETRY_NO_FALLBACK;
 
-  //@TODO: axes according to import settings
   opts.space_conversion = UFBX_SPACE_CONVERSION_ADJUST_TRANSFORMS;
   opts.target_axes.right = UFBX_COORDINATE_AXIS_POSITIVE_X;
   opts.target_axes.up = UFBX_COORDINATE_AXIS_POSITIVE_Z;

source/blender/io/fbx/importer/fbx_import_anim.cc

@@ -314,20 +314,8 @@ static void create_transform_curves(const FbxElementMapping &mapping,
     ufbx_transform xform = ufbx_evaluate_transform(fbx_anim, fnode, t);
 
     if (is_bone) {
-      /* For bones that have "ignore parent scale" on them, ufbx helpfully applies global scale to
-       * the evaluated transform. However we really need to get local transform without global
-       * scale, so undo that. */
-      if (fnode->adjust_post_scale != 1.0) {
-        xform.scale.x /= fnode->adjust_post_scale;
-        xform.scale.y /= fnode->adjust_post_scale;
-        xform.scale.z /= fnode->adjust_post_scale;
-      }
-
-      /* Bone transform curves need to be transformed to the bind transform
-       * in joint-local space. */
-      ufbx_matrix xform_mtx = ufbx_transform_to_matrix(&xform);
-      xform_mtx = ufbx_matrix_mul(&bone_xform, &xform_mtx);
-      xform = ufbx_matrix_to_transform(&xform_mtx);
+      ufbx_matrix matrix = calc_bone_pose_matrix(xform, *fnode, bone_xform);
+      xform = ufbx_matrix_to_transform(&matrix);
     }
 
     set_curve_sample(curves_pos[0], i, tf, float(xform.translation.x));

source/blender/io/fbx/importer/fbx_import_armature.cc

@@ -101,6 +101,9 @@ void ArmatureImportContext::create_armature_bones(const ufbx_node *node,
   this->mapping.el_to_object.add(&node->element, arm_obj);
   bone->flag |= BONE_SELECTED;
   bone->parent = parent_bone;
+  if (node->inherit_mode == UFBX_INHERIT_MODE_IGNORE_PARENT_SCALE) {
+    bone->inherit_scale_mode = BONE_INHERIT_SCALE_NONE;
+  }
 
   this->mapping.bone_to_armature.add(node, arm_obj);
 
@@ -304,11 +307,12 @@ void ArmatureImportContext::find_armatures(const ufbx_node *node)
             fbone, world_to_arm, found);
         if (found) {
           ufbx_matrix bind_local_mtx_inv = ufbx_matrix_invert(&bind_local_mtx);
-          ufbx_matrix local_mtx = fbone->node_to_parent;
+          ufbx_transform xform = fbone->local_transform;
           if (fbone->node_depth <= 1) {
-            local_mtx = ufbx_matrix_mul(&world_to_arm, &fbone->node_to_world);
+            ufbx_matrix matrix = ufbx_matrix_mul(&world_to_arm, &fbone->node_to_world);
+            xform = ufbx_matrix_to_transform(&matrix);
           }
-          ufbx_matrix pose_mtx = ufbx_matrix_mul(&bind_local_mtx_inv, &local_mtx);
+          ufbx_matrix pose_mtx = calc_bone_pose_matrix(xform, *fbone, bind_local_mtx_inv);
 
           float pchan_matrix[4][4];
           matrix_to_m44(pose_mtx, pchan_matrix);

source/blender/io/fbx/importer/fbx_import_util.cc

@@ -59,6 +59,27 @@ void m44_to_matrix(const float src[4][4], ufbx_matrix &dst)
   dst.m23 = src[3][2];
 }
 
+ufbx_matrix calc_bone_pose_matrix(const ufbx_transform &local_xform,
+                                  const ufbx_node &node,
+                                  const ufbx_matrix &local_bind_inv_matrix)
+{
+  ufbx_transform xform = local_xform;
+
+  /* For bones that have "ignore parent scale" on them, ufbx helpfully applies global scale to
+   * the evaluated transform. However we really need to get local transform without global
+   * scale, so undo that. */
+  if (node.adjust_post_scale != 1.0) {
+    xform.scale.x /= node.adjust_post_scale;
+    xform.scale.y /= node.adjust_post_scale;
+    xform.scale.z /= node.adjust_post_scale;
+  }
+
+  /* Transformed to the bind transform in joint-local space. */
+  ufbx_matrix matrix = ufbx_transform_to_matrix(&xform);
+  matrix = ufbx_matrix_mul(&local_bind_inv_matrix, &matrix);
+  return matrix;
+}
+
 void ufbx_matrix_to_obj(const ufbx_matrix &mtx, Object *obj)
 {
 #ifdef FBX_DEBUG_PRINT

source/blender/io/fbx/importer/fbx_import_util.hh

@@ -78,6 +78,10 @@ void node_matrix_to_obj(const ufbx_node *node, Object *obj, const FbxElementMapp
 void read_custom_properties(const ufbx_props &props, ID &id, bool enums_as_strings);
 void read_custom_properties(const ufbx_props &props, bPoseChannel &pchan, bool enums_as_strings);
 
+ufbx_matrix calc_bone_pose_matrix(const ufbx_transform &local_xform,
+                                  const ufbx_node &node,
+                                  const ufbx_matrix &local_bind_inv_matrix);
+
 //@TODO remove debug file print once things are working properly
 // #define FBX_DEBUG_PRINT